Rumen Artarski of Bulgarian electronics house Thrax is an extremist. No tolerance for half measures could be the motto above his office door though given their penchant for all things Thracian, it's more likely to be a kingly saying of antiquity*. He doesn't author multiples of anything. In each category Thrax offer just one model as their ultimate take on the subject. To date this includes 5½ components - the €15.000 Orpheus phono stage with triode-strapped NOS Siemens D3A pentode; the €15.000 Dionysos single-ended linestage with transformer volume and 6N6P triode gain; the €36.000/pr 70-watt class A push/pull interstage-coupled Spartacus monos with EML 520B direct-heated power triodes; the €24.000/pr class A push/pull Heros monos with transformer-coupled tube input and transformer-loaded Fet output; and the €24.000 32/384-capable DSP-controlled fully discrete R2R Maximinus DAC without output filter or buffer. If my counting scheme of 'point five' aroused visions of the Hogwarts Express departing London's King's Cross Station on platform 9¾ for Hogsmeade Station, that was deliberate. "I also have a SIT-based amp rather different from the crowd but not in production. I will be making a limited 13-piece run code-named UO-26 for 26 unobtainium devices which aren't for sale and only for close friends and staff and as a prize for our best business partners".
_______________________________________________________________________

* With shifting borders throughout the ages, Thrace as a geographical concept refers to a region defined by the Balkan mountains in the north, the Rhodope mountains and Aegean Sea to the south and the Black Sea and Sea of Marmara to the east. The biggest part of historical Thrace sits in present-day Bulgaria.The cunningly named Maximinus DAC echoes Maximinus Thraxwhom the Romans as their emperor from 235 - 238 called Gaius Julius Verus Maximinus Augustus.

From ebulliently machined bead-blasted aircraft-grade aluminium cases to complex power supplies and advanced transformers from the likes of Hashimoto, Lundahl, Plitron and Tamura/Tamradio, Thrax strategically bypasses the hunters and punters of 'good enough'. They aim instead at those who likewise pursue the hobby at an extremist level. Whilst there's zero excuse for a reviewer to call any €36.000 pair of amps value, as the firm's most expensive model it nonetheless separates Thrax from those who ply even more rarefied heights. Rumen's technology manifesto is a no-nonsense read—the core statement is "our products feature the minimum sensible number of stages implemented with the most linear devices operating in the closest to theoretically perfect operating conditions"—which ends with what you pay for and why it's a bargain: "Our products are very complex and use very special parts at substantial procurement cost. The price of our products directly reflects the cost of materials involved in their manufacturing and the time required to assemble them. All technology development is funded by other activities."

Heros assembly

Making their declaration of intent, tech beliefs and concomitantly applied solutions unmistakable, Thrax take a stand. This creates a sharp filter which allows prospective customers to agree or disagree without ambiguity. Those who 'pass' because they resonate with the expressed design goals next encounter the economical filter of fiscal ability and desire. Presto, the sophisticated well-off Thrax target audience (Artarski's reference system is anchored by Sonus faber's giant The Sonus faber flagship and a Continuum Audio Labs Criterion turntable). Whilst I'm personally more comfortable on the blue than white-collar side of said fence—I drive a 10-year old Subaru and rent—my own brand of 'moderate' (cough!) hifi extremism still considers a €15.000 statement linestage as just within the realm of justifiable ambition if it were to deliver true state-of-the-art performance and suffered no functional qualifications. As I've documented elsewhere, 2013 would be my personal year not of the snake but the valve preamp. Having found amplifier bliss in Nelson Pass' SIT-1 silicon-carbide single-stage/ended power Jfet SIT-1 monos, I'd sold off my remaining tube amps. My ongoing appreciation for valve virtues was thus keenly focused on low-level circuits.

Georgi Georgiev of the R&D team with assembled older tri-tube Dionysos on the bench

Correlating my personal headspace on desirable preamp features and functionality with the Thrax Dionysus made for nearly complete overlay of what my personal perfect preamp would be. Tube rectification is via 6C4P-EV/6Ц4П-В. Voltage stabilization is by constant current sources feeding a shunt regulator with a Maxim Semiconductor ultra low-noise voltage reference. Voltage amplification is via a single 6N6P/6Н6П. All this adds up to a very simple phase-inverting single-stage circuit in an attractively styled but also very serious chassis.

Metal work processing

green LED above input = 0° phase, red = 180°, amber = HT bypass

All its XLR i/o ports are transformer-coupled and there are two of each.
Individual ground-lift switches accompany the four RCA inputs and absolute phase may be set differently for each input. Like my Tap-X from Bent Audio's John Chapman, volume and balance control are via tapped transformers. Their 23 secondaries are relay-switched by microprocessor to span a range of -52dB to +18dB in 32 steps without any resistors in the signal path (unity gain equates to level 24, levels 25-32 operate in active mode).

Level settings are numerically confirmed with a green dual-mono display. Any dialed-in balance offset shows clearly with a 15:18-type split readout which tracks over all volume changes until changed again. The home-theater feature works by locking any selected input to its currently displayed output level whilst pressing 'mute' for five seconds (most such scenarios would select 24 for unity gain). Control for all on-the-fly switching between passive and active operation is implemented with costly Standex Meder reed relays. XLR/RCA outputs sadly cannot be used simultaneously. Either type is selected by switch. The fixed 'record' output—perhaps to a headphone amp—is properly buffered to avoid loading down the main circuit and unless engaged, not connected.

When Rumen suggested I review an entire Thrax system including his discrete resistor-ladder converter with USB plus the high-power hybrid mono amps, it took no arm twisting to sign on the dotted line for a 30-day loan after which the gear would be needed in Spain. Which segues this narrative neatly into the new models - the Heros monos which made their public debut in Seoul on the weekend of March 2nd/3rd; and the ambitious Maximinus converter which officially bowed during Axpona the following weekend.